The present invention relates to a multilayer component having an inductive impedance.
Conventional multilayer components having inductive impedance include structures formed by applying an Ag-based conductive paste for internal electrodes onto magnetic sheets consisting, for example, of an Nixe2x80x94Znxe2x80x94Cu ferrite material in a predetermined pattern, and laminating these magnetic sheets. Internal electrodes formed in adjacent magnetic sheets are connected to each other through via holes, thereby forming a coil in the laminate. On both ends of the laminate are also formed external electrodes connected to the internal electrodes.
A relatively large direct current must be passed through a device such as a choke coil or the like of a switching circuit. In conventional multilayer components having inductive impedance, however, a small direct current causes magnetic saturation to occur in a magnetic substance, thereby lowering the inductance values rapidly. Conventional multilayer components having inductive impedance are not suitable for applications that are required to pass a large direct current.
It is the object of the present invention to provide a multilayer inductor having characteristics that are only slightly degraded by magnetic saturation.
To attain this object, the present invention proposes a multilayer component having an inductive impedance comprising a laminate formed by laminating conductors that form a coil and insulators, in which the inductors are mutually connected so as to form a coil that has an axis in the laminating direction of the conductors; the laminate comprises a plurality of first insulators including a magnetic substance having a high magnetic permeability, and at least one second insulator that is located on the inner layer of the laminate and includes a magnetic substance having low magnetic permeability or a non-magnetic substance. The second insulator is located in the laminate in a manner that the inductor elements in regions divided by the second insulator in the laminating direction produce magnetic saturation caused by direct currents of substantially the same magnitude.
According to the present invention, since at least one second insulator that includes a magnetic substance of a low permeability or a non-magnetic substance is located on the inner layer of the laminate, a closed magnetic path is formed in each region divided by the second insulator(s). Although one large closed magnetic path is formed in the entire laminate in conventional multilayer inductors, magnetic fluxes from the divided regions are not combined or are significantly weakly combined in the multilayer component according to the present invention. A small closed magnetic path is formed in each region. Since the number of turns of the coil is about (1/number divided regions) of the total number of turns in each region divided by the second insulator(s), the magnetic field intensity in each region is also about (the square of 1/number of divided regions). Hence, the direct current value that causes magnetic saturation to occur can be increased compared with conventional multilayer inductors.
Also, since the inductance element in each region divided by the second insulator(s) causes magnetic saturation to occur in response to substantially the same direct current value, the multilayer inductor according to the present invention has a direct-current characteristic curve similar to the characteristic curve of one ordinary inductance element.
The other objects, constitution, and effect of the present invention will be described in detail below.